This invention is directed to a clear coating composition that uses a catalyst that minimizes yellowing after application and exposure to weathering.
Many modern automobiles have a color base coat finish, i.e. a finish containing pigments and a clear finish over the base coat. Coating compositions have been developed for the repair of these finishes that have properties similar to or the same as the original factory applied finish. One such repair finish or refinish composition is shown in Den Hartog, et al., U.S. Pat. No. 4,525,521 issued June 25, 1985. While the compositions of this patent have excellent physical properties that make them useful as high quality refinish composition, there is a problem of yellowing of the finish upon weathering when conventional catalysts are used such as phenols, resorcinols, boron trifluoride amine complexes, certain benzoates such as resorcinol monobenzoate and the like. Catalysts are required to be used in these compositions to decrease drying time and increase the rate of cure. With the color coat, yellowing is only a minor problem since the color pigments mask any yellowing but with the clear coat yellowing is a problem since it readily is visible.
There is a need for a catalyst that does not cause yellowing upon weathering and provides for an adequate "pot life". By "pot life" is meant the time the composition remains at useable application viscosity.